Increasing IIS connection limit
To increase the crappy limit of 10 concurrent connections to IIS (maximum allowed is 40 - which is the hard-coded limit) on Win XP, you can perform the following:
Find the adsutil.vbs script (should be in c:\inetpub\AdminScripts or similar) and run the following command at the command prompt:
adsutil set w3svc/MaxConnections 40
You can also download a utility that alters tcpip.sys from http://www.lvllord.de/. The app can be detected as a virus with some Ant-Virus software when it is not.